1. Field of the Invention
This invention relates to stereophonic pickup cartridges for simultaneously reproducing stereophonic recordings from a single-groove, two-channel record.
2. Description of the Prior Art
With reference to FIGS. 5 and 6, which represent prior art, the constructional features of one typical known stereophonic pickup cartridge are schematically shown. This pickup cartridge comprises four pole pieces, of which 21 is opposite to 22, and 23 to 24. Four coils, of which only 19 and 20 are shown for the sake of illustration, are wound on the four pole pieces respectively. A magnet armature 25 is movably supported by a damper member 26 in a magnetic gap formed by the pole pieces. The pickup cartridge comprises a cantilever 28 having one end equipped with a stylus 27 and the other end mounted integrally to the frontal end of the armature 25.
In such construction, it has been extremely difficult to locate the pole pieces 21 to 24 sufficiently close to the armature 25 and to reduce the length of the magnetic circuit, and thus magnetic efficiency remains low.
Furthermore, because the armature 25 is supported by the damper member 26 by way of planes, the fulcrum on which the armature 25 moves is indefinite, making it impossible to concentrate the mass of the vibration system at a point. This has set limitations on improvements in magnetic efficiency, frequency characteristic, cross-talk characteristic and distortion characteristic.